Mariculture for bacterial and organic waste removal: a field study of sponge filtering activity in experimental farming

Culture experiments in the field were performed on western Mediterranean populations of Ircinia variabilis and Agelas oroides. To evaluate culture and filtering performances among polluted and unpolluted sites in shallow waters, farming experiments were carried out in a harbour, a small tourist nautical base and a pristine biotope. Sponge explants were cultured onto nylon ropes, and in situ clearance rate tests were performed on farmed sponges to assess filtering ability under diverse farming conditions. At the harbour site, sponge survival and growth were similar to that observed in the two unpolluted sites until early summer, when a rapid increase in explant mortality occurred in response to extreme variations in environmental conditions. Filtering experiments revealed high retention and clearance rates of I. variabilis and A. oroides at all sites. The highest rates were observed at the polluted site, reflecting the optimal metabolic performance of explants in the first phase of culture under stressful conditions. Our results highlight the feasibility of sponge microcosms and the ability of I. variabilis and A. oroides to clear large volumes of water of organic and bacterial loads in polluted sites.     

Ammonia removal capacity of European natural zeolite tuffs: application to aquaculture waste water

Abstract. The possibility of improving aquaculture water quality using different kinds of zeolites is discussed. Zeolites are aluminosilicates, whose framework structure allows them to exchange cations. Cations have differing affinities for different structures, and in particular ammonia has a great affinity for phillipsite and clinoptilolite structures. These zeolites are already used for ammonia removal from municipal piggery, and aquacultural wastes. In the present paper, ammonia removal from aquacultural water from recirculating systems has been tested, comparing different zeolites under laboratory conditions. Phillipsite and clinoptilolite tuffs were effective in ammonia removal, while chabazitc tuff having a lower content of zeolitic material (50%) and lower affinity for ammonia showed that a lower temperature did not influence ion exchange capacity in any of the zeolites.     

Inflow and outflow water quality control in coastal aquaculture systems: a case study

Coastal water bodies are a particularly heterogeneous resource, typified by high spatial and temporal variability that could influence the aquaculture in coastal zones. However, the development of coastal aquaculture may produce negative impacts on the coastal area by the potential release of nutrients and organic matter that can be a source of pollution in receiving waters. The aim of this paper was to evaluate the performance of constructed wetland in controlling the dynamics of deoxygenating matter (organic matter and ammonia) and eutrophicating matter [organic matter and soluble reactive phosphorus (SRP)] in the waters entering (inflow) and flowing out (outflow) from a coastal aquaculture fish farm. We observed that constructed wetland systems are effective in removing fractions of total suspended solids, COD, total ammonia nitrogen and SRP contained in the inflow water with higher efficiency in the spring period (60.37%, 14.89%, 65.38% and 17.6% respectively) than in the summer period (45.10%, 8.06%, 32.43% and 8.00% respectively). Similar pattern was recorded for the treatment of the outflow waters, showing that the wetland system reduced most of the deoxygenating and eutrophicating matter produced as a consequence of feeding and fish metabolic activity. During the summer season, high algae mortality can reduce the performance of the wetland system in the outflow water control; this lower efficiency could be improved by controlling the biomass of algae by vegetation harvesting.     

工厂化对虾养殖池管式射流集污水力特性

工厂化养殖池内水体的流场分布特性直接决定了其对残饵、粪便等的排污性能。本实验研究了管式射流驱动模式下,射流角度与射流流速对养殖池内水体流场与污物聚集特性的影响。养殖池流场特性采用点式流速仪进行布点测量,利用MATLAB软件对流场特性进行分析。采用相机采集的养殖池集污效果图像,并利用Photoshop软件与自行开发的不规则图形面积分析软件对图像进行分析。研究表明,流速从池心向外呈"V"型变化,在射流角度固定的情况下,射流速度越大,池心低流速区域越小,污物向池心的聚集效果越好;在流速固定的情况下,存在一个最佳的射流角度,本实验在24 cm/s流速条件下,射流角度为40°时,池内污物聚集效果最优。结论认为在保证养殖对象生长的前提下,可尽量提高射流流速;在24 cm/s流速条件下,最佳射流角度在40°左右。本研究成果可为工厂化养鱼池、养虾池等管式射流水力驱动系统的优化设计提供参考依据。     

A review of the biophysical properties of salmonid faeces: implications for aquaculture waste dispersal models and integrated multi-trophic aquaculture

Knowledge of the quantitative and qualitative properties of salmonid faeces is necessary for aquaculture waste dispersal models, and the design of integrated multi-trophic aquaculture (IMTA) systems. The amount and proximate composition of salmonid faeces can be estimated using a mass-balance, nutritional approach. Indigestible components of salmonid diets have the potential to affect faecal 'cohesiveness' or 'stability'. Nutrient content and density of faeces can vary depending on diet and submersion time. Faecal density has a greater influence on settling velocity than faecal size. Published settling velocity data on salmonid faeces are highly variable due to differences in fish size, rearing systems, collection time, water density, methodology, the mass fraction tested and diet. Most faecal settling data used in published salmonid waste dispersal models are rudimentary and recent information suggests that such models are highly sensitive to this input. The design of open-water IMTA systems and estimation of nutrient capture and recovery from co-cultured filter feeders is difficult due to limited information on particle size, digestibility, settleable and non-settleable mass fractions of salmonid faeces at cage environments. Implications of faecal properties on the accountability for the effects of aquaculture nutrient loading are discussed.     

一株干酪乳杆菌对养殖水体亚硝酸盐去除机理的研究

为了解乳酸菌去除养殖水体亚硝酸盐的作用机理,实验研究了一株干酪乳杆菌L821a(Lactobacillus casei)对淡水鱼养殖水体亚硝酸盐的去除状况,通过对菌体、酶及代谢产物的实验,证明其去除亚硝酸盐的机理包括胞内酶作用、代谢产物乳酸的直接化学反应2H++3NO2-=NO3-+2NO↑+H2O作用和间接促进微生物反硝化作用3种作用机理。在养殖水体中主要以间接作用方式发挥作用。分析认为乳酸促进反硝化作用的原因在于为反硝化微生物提供了易于利用的有机碳源(能量物质)。     

美国低碳高效池塘循环流水精养新技术

为实现池塘循环水槽养殖模式的高效利用,降低养殖风险,文章开展了吉富罗非鱼(GIFT, Oreochromis niloticus)一年两造池塘循环水槽养殖研究。第一造吉富罗非鱼放养密度分别为183尾·m⁻²和274尾·m⁻²,规格为(36.6±2.8) g,养殖期为122 d;第二造吉富罗非鱼放养密度分别为154尾·m⁻²和215尾·m⁻²,放养规格为(185.2±15.8) g,养殖期为100 d;外池塘套养罗氏沼虾(Macrobrachium rosenbergii)、鲢(Hypophthalmichthys molitrix)和鳙(Aristichthys nobilis)。对养殖过程中的水质、养殖结果和效益进行评价分析。结果显示,第一造吉富罗非鱼成活率为83.38%,饵料系数1.12,养殖产量24 107 kg;第二造吉富罗非鱼成活率为93.35%,饵料系数1.17,养殖产量25 730 kg;外池塘罗氏沼虾2 012 kg,鲢1 789 kg,鳙801 kg;每公顷投入452 566元,收入655 099元,利润202 533元,投资回报率44.75%。研究表明,利用池塘循环水槽养殖模式开展吉富罗非鱼一年两造养殖,降低了链球菌发病率,提高了养殖效益,实现了养殖模式的高效利用。

     

循环水养殖系统管式射流集污特性试验研究

工厂化养殖池内的污物聚集效果是养殖池设计建造和运行管理的重要指标,对提升养殖技术和管理水平具有重要意义。针对一种典型的工厂化鱼类养殖池,对边侧管式射流系统驱动下的流场特性和污物聚集效果进行研究,探讨了射流角度、射流流速和循环抽吸方式等因素对养殖池内水体流场特性及污物聚集分布规律的影响。利用手持式ADV流速仪在养殖池内进行布点测量,获得各点流速数值,然后利用MATLAB软件进行流场插值构图,研究养殖池的流场分布特性;污物聚集特性采用图像法进行处理分析。研究表明:管式射流驱动作用下,流速从池心向外呈"V"型变化。在射流角度固定为40°条件下,射流速度越大,池心低流速区域范围越小,污物聚集效果越好。当射流速度达到0.3 m/s时,污物基本聚集于池心;在流速固定的情况下,对污物聚集效果存在一个最佳的射流角度,约为40°。池内循环抽吸模式对流场和污物聚集效果同样有着显著的影响。研究表明,采用底部抽吸时,排污孔附近的径向流速与切向流速均高于边侧抽吸模式,且污物聚集效果明显优于边侧抽吸模式。该研究成果可用于工厂化鱼类养殖池管式射流水力驱动系统的优化设计,在不影响养殖对象生长的前提下,可尽量提高射流流速,最佳射流角度一般为40°左右,并尽量采用底部抽吸模式。     

养殖水体中藻类的危害及其防治

随着鱼类养殖产量的大幅度提高，池塘有机物增多，塘泥增厚，水质日趋富营养化，藻类水华的发生率明显增加。由于藻类适应性强，繁殖速度快，一旦形成水华就比较难以治理，严重时可引起池塘鱼全部死亡。因此，养殖水体中藻类的危害应引起养殖者的高度重视。     

室内集约化养虾池以低频率运转水处理系统调控水质效果及氮磷收支

采用低频率运转循环水处理系统(含粗滤器、臭氧仪、气液混合器,蛋白分离器、暗沉淀池等)联用池内设施(微泡曝气增氧机与净水网)开展凡纳滨对虾室内集约化养殖实验。研究了养虾池以水处理系统调控水质效果及氮磷收支。结果表明,养虾水经系统处理后,NO₂-N(53.4%～64.5%)、COD_Mn(53.4%～94.4%)与TAN(31.6%～40.4%)被显著去除,有效改进虾池水质;养殖周期内未换水与用药,虾池主要水化指标均控制在对虾生长安全范围,7号实验池(100 d)与8号对照池(80 d)主要水化指标变化范围:DO分别为 5.07～6.70 mg/L和4.38～6.94 mg/L,TAN 0.248～0.561 mg/L和0.301～0.794 mg/L,NO₂-N 0.019～0.311 mg/L和0.012～0.210 mg/L,COD_Mn 10.88～21.22 mg/L和11.65～23.34 mg/L。7号池对虾生长指数优于8号池(80 d虾病暴发终止),单位水体产量分别为1.398 kg/m²与0.803 kg/m²。氮磷收支估算结果:7号与8号池饲料氮磷分别占总收入:氮93.70%与92.37%,磷98.77%与99.09%;初始水层与虾苗含氮共占总收入6.30%与7.63%,磷共占1.23%与0.91%。总水层(含排污水)氮磷分别占总输出:氮56.45%与59.86%,磷53.26%与55.79%;收获虾体氮磷分别占总输出:氮37.07%与31.94%,磷21.37%与13.11%。7号池饲料转化率较高;池水渗漏与吸附等共损失氮磷分别占总输出:氮7.00%与9.34%,磷25.37%与31.10%。实验结果表明,虾池以低频率运转循环水处理系统联用池内设施可有效控制水质与虾病,具较高饲料转化率。     

Formulation of aquaculture development at an ox-bow lake in Malaysia: economic feasibility analysis

Abstract. This paper summarizes the economic aspects of production models and discusses the economic feasibilities and some marketing requirements of a proposed fisheries-aquaculture development at an ox-bow lake, isolated from the Perak River, at Teluk Intan, Perak, Malaysia. Measures of feasibility from a budgetary simulation model are expressed in terms of net present values of return (NPV), internal rate of return (IRR) and return on sale; their changes recalculated in relation to practical ranges of variations in sale prices and yields, and under conditions of normal and 20% increment in operational costs, are also expressed. Using appropriate real production data, the cage culture complex has an NPV of M$4.068 million with an IRR of 68% and return on sales of 31% at a sale price of M$10/kg and yield of 12kg/m³ (US$1.00 = M$2.30); capture fisheries integrated with livestock have an NPV of M$252410, IRR of 42% and return on sales of 18% at a sale price of M$2.50/kg and yield of 33 tonnes; the hatchery facility has an NPV of M$0.963 million, IRR of 38% and return on sales of 20% at a sale price of M$0.39/fry and yield of 2 million; and prawn pond culture has an NPV of M$314000, IRR of 43% and return on sales of 36% at a sale price of M$11/kg and yield of 2.5 tons/ha. Overall, the modular project has an NPV of M$5.596 million with an IRR and return on sales of 53% and 28% respectively. Should the operational costs increase by 20% above normal, project unviabilities are obvious at specific levels: cage culture is unviable at sale prices ≤M$8.00/kg and yields ≤10 kg/m³; capture fisheries at sale prices ≤M$1.5/kg; hatchery facility at sale prices of fry ≤M$0.30/fry; prawn culture at sale prices ≤M$8.00/kg and yields ≤2 tons/ha; and the overall project is unviable when the sale level of fisheries products drops to 80% of the normal and operational costs increase to 120%. With greater efforts at raising sales and securing better prices, and raising yields while reducing operational costs, the projects have a markedly improved economic profit.     

A preliminary study on the potential value of a novel integrated aquaculture system on water purification

Intensive and semi-intensive sea cucumber aquaculture produces effluents that impact the quality of the local aquatic environment and sea cucumber growth; such effluents are an important cause of coastal water eutrophication. Integrated aquaculture has been shown to efficiently reduce the release of nutrients during aquaculture and to provide economic benefits. In this study, we report our investigation of a polyculture system utilizing Styela clava (stalked sea squirt) and Stichopus japonicus (Japanese sea cucumber) under two feeding modes. To examine purification of the water in the system, nutrients in the water and the sediment, attached heterotrophic bacteria, and the survival rates and growth rates of S. clava and S. japonicus were determined. Tank cultivation trials showed that, under the same feeding modes, the concentration of nutrients in the polyculture system was approximately 50–60 % of the sum of the nutrients in the S. japonicus mixture and S. clava monoculture systems. The abundance of attached heterotrophic bacteria in the polyculture system was remarkably lower than that of the mixed culture system under the same feeding mode. S. japonicus in the polyculture system grew better than those in the mixed culture system under the same feeding mode. These results demonstrate that the S. clava–S. japonicus integrated culture system offers a means of constraining or reversing the pollutive impacts of coastal sea cucumber aquaculture.     

American eel, Anguilla rostrata, growth in fresh and salt water: implications for conservation and aquaculture

Abstract  Growth of American eels, Anguilla rostrata (Lesueur), sampled in saltwater bays and adjacent freshwater ponds in the southern Gulf of St. Lawrence, Canada, was estimated by otolith annulus back-calculation, and related to salinity of growth habitat as determined using otolith strontium:calcium ratios. Eels resident in salt water grew on average in length 2.2 times faster than freshwater residents and increased in weight 5.3 times faster than freshwater residents. Previous findings of superior American eel growth rate in brackish water are thus extended to full-strength salt water. Freshwater residents took an estimated 2.4 times longer than saltwater residents to reach the silver eel stage. The extended time to maturation of eels reared in fresh water increases their vulnerability to fisheries and to bio-accumulation of contaminants. Freshwater eel populations should be managed more conservatively than those in saline waters. The increase in eel growth with salinity suggests that rearing in brackish or salt water could improve growth rates in eel aquaculture.     

固定化微生物修复养殖池塘污染底泥的围隔试验

摘要：通过测定上覆水的多项水质指标、底泥总有机碳(TOC)、底泥生物降解能力(G值)、底泥异养细菌数和反硫化细菌数等指标值,在野外实验围隔条件下比较了固定化微生物和游离微生物（FR-M）对污染底质的生物修复能力。微生物固定所用载体包括：纤维网状活性炭,生物活性炭,沸石和硅藻土(相应的固定化微生物分别标记为FC-M、 BC-M、ZE-M和DI-M组)。结果显示：固定化微生物对围隔内水质有间接影响,试验后期固定化微生物组（ZE-M、DI-M和FC-M组）的上覆水硝氮浓度显著高于对照组;BC-M组和ZE-M组上覆水中的COD值显著低于游离微生物组(FR-M)和对照组,说明固定化微生物有效削减了水底界面还原性物质的污染程度;与游离微生物或对照组相比,固定化微生物组（FC-M组、DI-M 组和ZE-M组）能更有效地降解底泥有机质。固定化微生物对底泥生物降解能力（G值）的影响明显,实验后期固定化微生物组（（BC-M组、DI-M组和ZE-M组）的G值均显著高于对照组和游离微生物组,说明固定化微生物技术的运用显著提高了围隔底泥的生物降解能力;固定化微生物对围隔内底泥异养细菌总数影响不显著,可能是由于底泥微生物群落结构受其它多种因子的综合影响所致。固定化微生物对底泥反硫化细菌影响显著,与对照组和游离微生物组相比,固定化微生物（尤其是ZE-M和BC-M组）能更有效地减少围隔底泥反硫化细菌数。本实验结果显示,利用载体固定微生物技术能显著提高微生物对污染底质的生物修复能力,其中以ZE-M和BC-M组效果最好。     

生物净化剂对养殖水体亚硝酸盐含量影响的研究

本实验研究了三种有益菌 :光合细菌 (Photosyntheticbacteria ,PSB)、芽胞细菌 (Bacillus,BAC)、放线菌 (Actinobacillus,ACT)对养殖水体中亚硝酸盐含量的影响。结果表明 :随着有益菌使用剂量的增加 ,水中亚硝酸盐的含量逐渐降低。证明了三种有益菌都有净化水质的作用 ,ACT的净化效果优于PSB和BAC。     

Alum residuals as a low technology for phosphorus removal from aquaculture processing water

Aquaculture process waters are often scrutinized for loading phosphorus discharges into surface water. With the growing regulatory control of discharge from aquaculture process industries, it has become very important to address low cost and effective technological solution for aquaculture facilities. This study aims to investigate the effectiveness of alum residuals, which were generated during drinking water treatment for adsorption of phosphorus from aquaculture process water. Alum residuals were dried using an oven at 105 °C for 24 h. Particle size (d₆₀) was similar to conventional adsorbent, granular activated carbon. Bench scale experiments (batch and fixed bed column tests) were conducted using oven dried alum residuals. Fixed bed column tests also looked at the effect of influent pH on the effectiveness of oven dried alum residuals. Experimental results observed phosphorus removal of 94–99% using an alum residuals concentration of 4–16 g/L. Freundlich adsorption isotherm was effective in explaining partitioning among solid and liquid phases. Oven dried alum residuals were a better adsorbent for orthophosphate phosphorus than total phosphorus. Effluent pH levels for both batch and fixed bed column tests were within range of 6–9 for most of the samples tested and therefore, suitable for surface water disposal. There were no effects of pH observed on the breakthrough pore volume processed during fixed bed column test. There was aluminum leaching from oven dried alum residuals, however, not high enough to cause toxicity for aquatic species if disposed in surface water. Oven dried alum residuals were also able to adsorb organic matter from aquaculture process water. The effluent BOD₅ was below 30 mg/L for most of the samples with an exception of a few samples where BOD₅ was beyond the limit for surface water disposal guidelines. The results indicated that oven dried alum residuals have potential to provide a technological solution for small aquaculture facilities.     

Use of intensive rearing systems as back-up for coastal lagoon aquaculture: an experience with eels, Anguilla anguilla L., in the Comacchio lagoons

Abstract. The possibility of using eels from intensive rearing ponds to restock natural basins has been investigated by comparing growth, survival and rate of yellow-to-silver metamorphosis of 'wild type' eels and of eels from an intensive rearing pond. A total of 2243 marked eels were released into a closed natural environment of 22ha; 1254 were wild type (average length 45·6 ± 9·0cm), and 989 from an intensive rearing pond, split by a mechanical grader in two groups. The first group was made of 617 well-growing eels (44·9 ± 3·0cm), the second one of 372 smaller eels (36·9 ± 4·3cm) which had not adapted to the artificial conditions.
The starting size being equal the animals grew to the same extent; in some cases the animals previously adapted to the artificial pond grew better than the wild type. The rate of metamorphosis from yellow to silver eel was 28·4% for the wild type eels and 22% for the others, although the latter became mostly silver males. Survival of the wild type eels (starting with the 35-cm size class and covering the period from April to December) was calculated by mark-recapture at approximately 98·6%. For the eels previously well adapted to the intensive rearing pond it was only 85%, indicating some difficulty in competing in the natural environment. The good growth shown by the smaller eels, with a survival of about 90%, would seem to indicate that these animals might be effectively used for restocking purposes, thus favouring an integration between the intensive ponds and the extensive environments.     

Monitoring water quality for tropical freshwater fisheries and aquaculture: a review of aircraft and satellite imagery applications

Abstract  Water quality in tropical fish ponds is generally evaluated without the assistance of remote sensing because of cost, cloud cover, and other constraints, but certain parameters such as suspended solid concentrations, colour, chlorophyll and temperature can effectively be monitored by aerial photography and satellite imagery. This paper reviews applications of remote sensing to tropical inland fisheries and aquaculture and includes applications from related disciplines. A brief assessment of new platforms and sensors is also presented. Remote sensing images may help to inform researchers and planners about water quality trends that are occurring over a broad area in which fisheries and aquaculture activities occur. However, the operational use of remote sensing in aquaculture remains largely experimental.     

Land suitability evaluation for brackish water aquaculture development in coastal area of Hormozgan,Iran

Land suitability analysis is a prerequisite for successful aquaculture, and site selection affects both the success and sustainability of any aquaculture development. There is an urgent need for appropriate methodology to assist planners for site selection in aquaculture development. Site selection can be viewed as a multi-criteria decision-making (MCDM) problem. The analytical hierarchy process (AHP) is a proven, effective method used to solve problem of site selection. This paper applied geographic information systems (GIS), the AHP method, and MCDM to identify areas that are suitable for shrimp aquaculture development in coastal area of Hormozgan, Iran. To create models, combination of layers was carried out through Boolean operators and weighted linear combination (WLC) method. After performing the combination models, the results are presented and compared. Evaluation of the results shows that the most of the areas classified suitable in WLC model coincide with the existing shrimp farms and this indicates the validity of the GIS-based WLC model. The areas with the highest priorities are situated in eastern part of the study area. Since existing shrimp farms cover a small extent in the study area, further expansion of shrimp farming to other areas is possible.